1. Field of the Invention
The present invention relates to an object search apparatus which searches for objects scattered in an environment.
2. Description of the Related Art
There are many robot systems, including those for industries and researches, which sense the positions of target objects by using visual information and the like and control manipulator apparatuses on the basis of detected information. Assume that a robot system is introduced into a home to fetch objects such as eating utensils and PET bottles and to carry them to other places. In this case, a target object is not necessarily located in a place where the robot can see it. In many cases, such objects are placed in a cabinet or a refrigerator. In order to reliably find a target object in such a situation, it is necessary to comprehend, in some form, the inclusion relationship or positional relationship (to be referred to as a hierarchical relationship hereinafter) between objects, which indicates that, for example, an object A is placed in an object B (or on object B).
According to a technique of managing the hierarchical relationship between objects, which is disclosed in, for example, JP-A 2007-34356, radio-frequency identification (RFID) tags are attached to search target objects in advance, and tag readers are installed in predetermined places such as shelves. When each object is placed on a given shelf, the tag reader set on the shelf reads the RFID tag information of the object. A hierarchical relationship indicating that the object is placed on the shelf is then stored. The respective tag readers installed on the respective shelves are managed hierarchically in advance, and the hierarchical relationship between the respective objects and the shelves on which the objects are placed is stored in the above manner, thereby managing a specific object as a target object with hierarchical position information, for example, indicating that the object “is in the third drawer of a cabinet A”.
Assume that the positions of a plurality of objects are hierarchically managed in this manner. In this case, when, for example, a desired object in the third drawer of the cabinet A is to be found, the shelf A is found first, and the third drawer of the cabinet A is found next. The desired object is then found from the drawer. In this manner, it is possible to search for a desired object in a proper sequence in consideration of the hierarchical structure within a short period of time. It can therefore be expected to greatly improve the reliability of reaching the desired object.
In order to manage the positions of a plurality of objects in the above manner by storing, in advance, them by using the hierarchical structure of a storage facility such as a cabinet and its drawers in which the plurality of objects are stored, it is necessary to install tag readers, in advance, at the respective storage positions on the respective object shelves, in the drawers, and the like. In addition, it is necessary to use a database for storing the hierarchical relationship of all the installed tag readers and the position information of each object detected by a corresponding tag reader. This is a feasible arrangement. However, an apparatus used to implement such an arrangement is very large in scale in a small-scale environment such as a home.
As described above, the conventional problem is that it is impossible to easily search for a plurality of objects (e.g., vessels and tools) scattered in a relatively small-scale environment such as a home (residence) by using a hierarchical positional relationship.
The present invention has therefore been made in consideration of the above problem, and has as its object to provide an object search apparatus and method which can easily search for a plurality of scattered objects.